My nearly 10-year-old Acer desktop has an intermittent startup problem. After being transported or after I turn the UPS back on, pressing the power button may do nothing at all. Sometimes it responds after a delay, starts the fans, then shuts down and repeats a restart cycle. The same computer starts normally at the repair shop, even after several test restarts, but may fail again as soon as I bring it home. Leaving it powered off for many hours sometimes makes it start normally the next day.
I have tried different wall outlets, another house, the UPS, direct wall power, and disconnecting peripherals. The outlets and UPS appear to work, and the UPS handles brief outages normally. The issue seems to occur mainly after transporting the PC and switching the UPS off and on. The UPS battery was recently replaced, but the behavior also occurred when it was new.
The system is an Acer desktop with an i7-8700 and GTX 1050. I have replaced the RAM, cooling fan, and CMOS battery. I also previously saw a CMOS checksum or battery-loss warning; the old battery measured about 2.2 volts. When the problem occurs, the fans may spin briefly before shutdown, and on one occasion there were two beeps followed by the CMOS warning. Could the power supply, motherboard, case wiring, UPS, or transportation be causing this? Is there any realistic risk of damaging the RAM, and should I be looking at replacing the storage drive or another component?
4 Answers
The CMOS warning is important. A healthy CR2032 should be close to 3 volts when measured out of circuit; around 2.2 volts is low. However, replacing the battery would not explain a completely dead power button by itself. The beep code and checksum message could indicate that the motherboard is losing settings or power during the failed startup, so the board or PSU may be deteriorating.
A UPS can mask some power problems, but it should not require a 12-hour warm-up before the PC works. Check that the UPS output type and capacity are suitable for the computer, and try a controlled test with the PC connected directly to a known-good wall outlet while the UPS is completely removed. If the fault follows the PC, the UPS is probably not the main cause. Given the age of the system and the repeatable transport-related behavior, I would have the PSU tested or replace it with a known-good quality unit before buying more RAM.
A storage drive or RAM problem would not normally prevent the power button from doing anything. RAM can cause a failed POST, but the fans and power should generally come on. Since you sometimes get no response at all, the power supply, motherboard, front-panel switch, or a loose internal connection is more likely than the drive.
That makes sense. The odd part is that the shop can restart it repeatedly without reproducing the problem, while transporting it home seems to trigger it.
Transporting the case may be disturbing a marginal connection. With the PC unplugged, reseat the RAM, power cables, graphics card, and any modular PSU cables, and inspect the motherboard for damaged components or a loose screw. Also check the small front-panel power-switch connector. If possible, test by briefly shorting the two power-switch pins with a screwdriver; if that works reliably, the case switch or its wiring is faulty.
I would test the replacement battery with the PC unplugged rather than relying only on a software reading. If it is good, focus on the PSU and motherboard instead of replacing the storage drive.